Toner level detector

ABSTRACT

A detector for providing an operator of an electrostatographic copier with an early warning of impending exhaustion of the supply of toner in the reservior of a toner dispenser comprises a flexible member bridged across the reservior for actuating a switch to, in turn, activate a suitable indicator when the supply of toner drops below a predetermined level.

United States Patent [191 Sugawara Nov. 18, 1975 1 TONER LEVEL DETECTOR [75] Inventor: Kiyoshi Sugawara, Ebina, Japan [73] Assignee: Rank Xerox, Ltd., London, England [22] Filed: Mar. 15, 1974 [21] Appl. No.: 451,633

[30] Foreign Application Priority Data Sept. 5, 1973 Japan 48-103486 [52] US. Cl 222/23; 222/232 [51] Int. Cl. B67D 5/32; G01F 11/00 [58] Field of Search 222/56, 64, 65, 66, 23,

[56] References Cited UNITED STATES PATENTS 2,399,228 4/1946 lrmscher 214/17 CA gamm it.

3,110,420 11/1963 Brewer ..222/56 3,253,745 5/1966 Skelton. 222/56 3,422,768 l/1969 Repp..... 222/56 X 3,632,019 l/1972 Harm 222/64 X Primary ExaminerStanley H. Tollberg Assistant Examiner1-1add Lane [57] ABSTRACT A detector for providing an operator of an electrostatographic copier with an early warning of impending exhaustion of the supply of toner in the reservior of a toner dispenser comprises a flexible member bridged across the reservior for actuating a switch to, in turn, activate a suitable indicator when the supply of toner drops below a predetermined level.

9 Claims, 4 Drawing Figures US. Patent Nov. 18,1975 Sheet10f2 3,920,154

FIG. I

U.S. Patent Nov. 18, 1975 Sheet 2 of2 3,920,154

FIG. 4

TONER LEVEL DETECTOR BACKGROUND OF THE INVENTION This invention relates to toner dispensers for electrostatographic copiers and duplicators and, more particularly, to detectors for warning a machine operator of impending exhaustion of the toner supply.

Conventional electrostatographic copiers and duplicators (hereinafter jointly referred to as copiers) use an electroscopic toner to develop the latent electrostatic image from which the copy is made. Toner is, therefore, necessarily consummed in the copying process, thereby depleting the toner supply. When the supply of toner finally nears exhaustion, there is a perceptible reduction in the density of the developed image and, therefore, a corresponding degradation of the copy quality. That is usually the first indication that the toner supply is in need of replenishment. A knowledgeable operator will, of course, add additional toner upon noticing that the density of the copied image has decreased, but several substandard copies may be made before that happens.

Accordingly, it has been recognized that an earlier warning of impending toner exhaustion would be desirable. One approach to solving that problem has been to use a transparent toner dispenser so that light emitted by a lamp at one side of the dispenser is visible at the other side when the toner supply drops below a predetermined level. Another proposal has been to provide an out of toner indication when the density of the developed image does not materially increase after repeated calls from an automatic development control system for additional toner. Still an additional suggestion has been to monitor the toner dispenser electronically to detect the change in dielectric coefficient which takes place when the gap between two spaced apart plates in the toner dispenser is occupied by air rather than by toner.

SUMMARY OF THE INVENTION An object of this invention is to provide a reliableand economical detector, which drains little if any power when in a standby condition, but which still supplies an early warning of impending exhaustion of the toner in a toner dispenser.

To achieve that and other objects of the present invention, a flexible member is bridged across the reservior of a toner dispenser so that it is gradually unloaded as the toner is consummed. When the toner level reaches a predetermined low level, the flexible member actuates a switch to thereby activate a suitable indicator, such as a lamp.

BRIEF DESCRIPTION OF THE DRAWINGS I penser taken along the line 4-4 in FIG. 1.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT While the invention is described in some detail hereinafter with specific reference to a single embodiment, it should be understood that there is no desire to limit it to that embodiment. On the contrary, the intent is to cover all modifications, alternatives and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

Turning now to the drawings, it will be seen that there is a toner dispenser 11 having a roll 12 which is rotatably driven (by means not shown) to discharge granular toner material 13 through a constricted opening at the bottom of a hopper-like reservior 14. A detector 15 provides the operator with a warning whenever the supply of toner 13 in the reservior 14 falls below a predetermined level, thereby encouraging the operator to replenish the toner supply before there is any perceptible change in the copy density. The additional toner that may be needed from time-to-time is added through an opening 16 at the top of the reservior 14.

in accordance with this invention, the detector 15 includes a pressure responsive switch 21 and a flexible member 22 which is bridged between the opposite ends 23 and 24 of the reservior 14 to actuate the switch 21 when the supply of toner 13 in the reservior 14 drops below a predetermined level. A suitable indicator, such as a lamp (not shown), is activated when the switch 21 is actuated, thereby providing the operator with a warning of impending exhaustion of the toner supply.

More particularly, in the illustrated embodiment, the flexible member 21 comprises a pair of flexible rods 25 and 26 for supporting a plurality of generally horizontal plates 27 in spaced apart relationship between the opposite ends 23 and 24 of the reservior 14. One end of each of the rods 25 and 26 is anchored to an end 23 of the reservior l4 and the other end of each of them is connected to a plunger 28, which in turn, is guided in an outwardly opening cavity 29 at the opposite end 24 of the reservior 14. The switch 21, which is typically a microswitch, is mounted (by means not shown) adjacent the cavity 29 so that its actuator 31 is aligned with the plunger 28, and the plunger 28 is biased toward the switch actuator 31 by a spring 32.

In keeping with one of the more detailed aspects of this invention, the plates 27 are nested between a pair of substantially vertical baffles 33 and 34 which are held in generally parallel alignment with the forward and rearward sidewalls 35 andd 36, respectively, of the reservior 14 by its end 23 and 24. Thus, when toner 13 is initially loaded into the reservior 14, or when the toner supply is replenished, some of the toner 13 comes to rest on the plates 27, but most of the balance is deflected outwardly by the baffles 33 and 34 toward the forward and rearward sidewalls 35 and 36. Accordingly, as shown in FIGS. 2 and 3, the space directly beneath the plates 27 is relatively free of toner 13, thereby enabling the rods 25 and 26 to flex downwardly into that space under the influence of the loading effect of the toner 13 on the plates 27. Of course, the downward flexure of the rods 25 and 26 overcomes the bias supplied by the spring 32 to pull the plunger 28 away from the switch actuator 31.

To maintain a flow of toner 13 through the reservior 14, the rods 25 and 26 are vibrated from time-to-time during operation of the dispenser 11. This feature of the invention is carried out by providing a pair of rigid elastic fingers 37 and 38 for tapping the rod 25 so that toner 13 tends to spill off the plates 27 into the lower part of the reservior 14. The fingers 37 and 38 are secured to a shaft 39 and each of them has its upper end adjacent the rod 25 and its lower end riding in a respective one of a pair of annular grooves 41 and 42 in the dispenser roll 12. The shaft 39 is journalled in the ends 23 and 24 of the reservior 14, and each of the grooves 41 and 42 has one or more projections 43 for engaging the lower ends of the fingers 37 and 38. Consequently, as the dispenser roll 12 rotates in, say, a counter-clockwise direction (as viewed in FIG. 1), the shaft 39 tends to rotate in a clockwise direction. Connected between the reservior l4 and the shaft 39, however, there is a spring 44 which resists the rotation of the shaft 39 in that direction. Therefore, when the lower ends of the fingers 37 and 38 engage the projections 43, the shaft 39 initially rotates counter-clockwise to swing the upper ends of the fingers 37 and 38 away from the rod 25 and then snaps back in the other or clockwise direction to swing the upper ends of the fingers 37 and 38 against the rod 25.

As will be appreciated, the supply of toner 13 in the reservior 14 is gradually depleted in operation. Thus, the load on the plates 27 is gradually reduced, thereby permitting the rods 25 and 26 to slowly straighten. That, in turn, causes the plunger 29 to move toward the switch actuator 31 such that the plunger ultimately actuates the switch 21 when the toner supply 13 drops below a predetermined level. As previously mentioned, a suitable indicator (not shown) is activated at that point to warn the operator of impending exhaustion of the toner supply.

CONCLUSION In view of the foregoing,,it will now be understood that the present invention provides a relatively simple and reliable detector which may be advantageously utilized in the toner dispenser of an electrostatographic copier to warn the operator of impending exhaustion of the toner supply before there is any'perceptible change in the density of the copied image.

What is claimed is:

1. In a toner dispenser having a reservoir for storing a supply of toner, a detector for sensing impending exhaustion of the toner supply; said detector comprising the combination of a flexible member horizontally bridged between opposed ends of said reservoir to flex downwardly in response to loading thereofby said supply of toner, a pair of substantially vertical baffles disposed on opposite sides of said flexible member for maintaining a space below said member to accomodate downward flexure of said member when said member is loaded with toner, and a switch positioned to be actuated by said member when said supply of toner drops below a predetermined level.

2. The toner dispenser and detector of claim 1 wherein said flexible member comprises a plurality of substantially horizontal plates for supporting toner in an upper area of said reservior: and further including means for vibrating said plates from time-totime to 4 thereby maintain a flow of toner from said upper area to a lower area of said reservior as toner is discharged by said dispenser.

3. The toner dispenser and detector of claim 1 wherein said flexible member is flexed downwardly into said space under the weight of toner supported in an upper area of said reservoir: and further including means for maintaining a flow of toner from said upper area of said reservoir as toner is discharged by said dispemser. I

4. The toner dispenser and detector of claim 3 wherein said flexible member comprises a plurality of substantially horizontal plates supported in spaced apart relationship between the opposed ends of said reservior, and said flow maintaining means includes means for vibrating said platesfrom time-to-time as toner is discharged by said dispenser.

5. The toner dispenser and detector of claim 1 wherein said flexible member comprises a plurality of generally horizontal plates and a flexible rod for supporting said plates in spaced apart relationship between the opposed ends of said reservoir.

6. The toner dispenser and detector of claim 2 further including a plunger, an outwardly opening cavity at one end of said reservior for guiding said plunger, and means for biasing said plunger away from said reservior; and wherein said switch is a pressure sensitive switch having an actuator aligned with said plunger, and said plunger is connected to one end of said rod, whereby said plunger ultimately engages the switch actuator as the level of toner in said reservior is reduced.

7. The toner dispenser and detector of claim 6 further including a rotatably driven roll for dispensing toner from said reservoir, said roll having an annular groove with at least one projection extending outwardly therefrom: and wherein said finger has one end riding in said groove, whereby said shaft is rotated first in said one direction and then released to rotate in the opposite direction as the end of said finger engages with and disengages from, respectively, said projection.

8. The toner dispenser and detector of claim 5 further including a shaft journalled in the opposed ends of said reservior, a finger secured to sadi shaft and extending therefrom into adjacent relationship with said rod, means for biasing said shaft against rotation in one direction, and means for rotating said shaft from time-totime against said bias and for then releasing said shaft to rotate in the opposite direction so that said finger snaps back against said rod, whereby said rod and plates are vibrated from time-to-time to maintain a flow of toner from an upper area to a lower area of said reservior as toner isdischarged by said dispenser.

9. The toner dispenser and detector of claim 8 further including a plunger, an outwardly opening cavity at one end of said reservoir for guiding said plunger, and means for biasing said plunger away from said reservoir; and wherein said switch is a pressure sensitive switch having an actuator aligned with said plunger, and said plunger is connected to one end of said rod, whereby said plunger ultimately engages the switch actuator as the level of toner in said reservoir is reduced. 

1. In a toner dispenser having a reservoir for storing a supply of toner, a detector for sensing impending exhaustion of the toner supply; said detector comprising the combination of a flexible member horizontally bridged between opposed ends of said reservoir to flex downwardly in response to loading thereof by said supply of toner, a pair of substantially vertical baffles disposed on opposite sides of said flexible member for maintaining a space below said member to accomodate downward flexure of said member when said member is loaded with toner, and a switch positioned to be actuated by said member when said supply of toner drops below a predetermined level.
 2. The toner dispenser and detector of claim 1 wherein said flexible member comprises a plurality of substantially horizontal plates for supporting toner in an upper area of said reservior: and further including means for vibrating said plates from time-to-time to thereby maintain a flow of toner from said upper area to a lower area of said reservior as toner is discharged by said dispenser.
 3. The toner dispenser and detector of claim 1 wherein said flexible member is flexed downwardly into said space under the weight of toner supported in an upper area of said reservoir: and further including means for maintaining a flow of toner from said upper area of said reservoir as toner is discharged by said dispenser.
 4. The toner dispenser and detector of claim 3 wherein said flexible member comprises a plurality of substantially horizontal plates supported in spaced apart relationship between the opposed ends of said reservior, and said flow maintaining means includes means for vibrating said plates from time-to-time as toner is discharged by said dispenser.
 5. The toner dispenser and detector of claim 1 wherein said flexible member comprises a plurality of generally horizontal plates and a flexible rod for supporting said plates in spaced apart relationship between the opposed ends of said reservoir.
 6. The toner dispenser and detector of claim 2 further including a plunger, an outwardly opening cavity at one end of said reservior for guiding said plunger, and means for biasing said plunger away from said reservior; and wherein said switch is a pressure sensitive switch having an actuator aligned with said plunger, and said plunger is connected to one end of said rod, whereby said plunger ultimately engages the switch actuator as the level of toner in said reservior is reduced.
 7. The toner dispenser and detector of claim 6 further including a rotatably driven roll for dispensing toner from said reservoir, said roll having an annular groove with at least one projection extending outwardly therefrom: and wherein said finger has one end riding in said groove, whereby said shaft is rotated first in said one direction and then released to rotate in the opposite direction as the end of said finger engages with and disengages from, respectively, said projection.
 8. The toner dispenser and detector of claim 5 further including a shaft journalled in the opposed ends of said reservior, a finger secured to sadi shaft and extending therefrom into adjacent relationship with said rod, means for biasing said shaft against rotation in one direction, and means for rotating said shaft from time-to-time against said bias and for then releasing said shaft to rotate in the opposite direction so that said finger snaps back against said rod, whereby said rod and plates are vibrated from time-to-time to maintain a flow of toner from an upper area to a lower area of said reservior as toner is discharged by said dispenser.
 9. The toner dispenser and detector of claim 8 further including a plunger, an outwardly opening cavity at one end of said reservoir for guiding said plunger, and means for biasing said plunger away from said reservoir; and wherein said switch is a pressure sensitive switch having an actuator aligned with said plunger, and said plunger is connected to one end of said rod, whereby said plunger ultimately engages the switch actuator as the level of toner in said reservoir is reduced. 